Apple is often criticized for selling its chargers at a high profit margin, especially when you can easily find an incredibly cheap version on eBay. Well, it turns out there’s a reason these counterfeiters can make such cheap chargers. Engineer Ken Shirriff tore down an Apple-branded iPad charger and a counterfeit version, and he found that the counterfeit version skimps on power quality, construction, and safety. The counterfeit charger, which advertised itself as a 10W charger, was in fact just a 5W charger.

Shirriff explains how chargers work in incredible detail and accompanies his teardown with pictures that show the generally lower-quality production value of the counterfeit charger. The counterfeit charger has fewer parts, less insulation around the parts, and parts that are “visibly crooked or askew.”

Shirriff also offers his own recommendations for chargers. While he of course doesn’t recommend the counterfeits, he also believes Apple’s official chargers may not be worth it either.

“Non-Apple name brand chargers are generally good quality according to my tests, with some better than Apple,” he said. “If you want to get an Apple charger without the high price, the best way I’ve found is to buy a used one on eBay from a U.S. source.”